Method, device, and communication system for establishing connection with network management system

ABSTRACT

The present disclosure relates to the field of communications technologies and discloses a method, a device, and a communication system for establishing a connection with a network management system. The method includes: obtaining, by a relay node, a first IP address of the relay node; obtaining, by the relay node, an IP address of a security gateway by using the first IP address of the relay node; establishing, by the relay node, an IP security tunnel with the security gateway according to the IP address of the security gateway; obtaining, by the relay node, a second IP address of the relay node and an IP address of the network management system through the IP security tunnel; and establishing, by the relay node, a connection with the network management system by using the second IP address of the relay node and the IP address of the network management system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2012/072831, filed on Mar. 22, 2012, which claims priority toChinese Patent Application No. 201110077281.7, filed on Mar. 29, 2011,both of which are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to the field of communicationstechnologies and, in particular, to a method, a device, and acommunication system for establishing a connection with a networkmanagement system.

BACKGROUND

In the process of broadband and mobilization development of a network,the 3rd Generation Partnership Program (3rd Generation PartnershipProgram, 3GPP) organization introduces the Long Term Evolution (LongTerm Evolution, LTE) solution, namely Evolved Universal MobileTelecommunication System (UMTS) Territorial Radio Access Network(Evolved Universal Mobile Telecommunication System Territorial RadioAccess Network, E-UTRAN), for a mobile access network, and introducesthe System Architecture Evolution (System Architecture Evolution, SAE)scheme, namely Evolved Packet Core (Evolved Packet Core, EPC), for amobile core network.

A conventional cellular network is a base-station-centered star topologynetwork and uses centralized control. Therefore, a problem about relaynode access does not exist in an access network. In an LTE system, arelay node (Relay Node, RN) is introduced in an access network to extendthe network coverage, increase network capacity, and improve flexibilityof network deployment. In the process of a relay node accessing thenetwork, the relay node needs to establish a connection with a networkmanagement system, such as an operation and management (Operation andManagement, OAM) system, and then download a configuration parameterfrom the network management system to implement the access andconfiguration of the relay node. Meanwhile, the security of theconnection between the relay node and the network management system andthe security of the connection establishing process need to be furtherensured. However, in the prior art, there is no implementation schemeabout how to establish a connection between a relay node and a networkmanagement system.

SUMMARY

To resolve the foregoing problem existing in the prior art, embodimentsof the present disclosure provide a method, a device, and acommunication system for establishing a connection with a networkmanagement system, so as to implement a connection between a relay nodeand a network management system and ensure the security of the relaynode and a correct network access.

For this purpose, an embodiment of the present disclosure provides amethod for establishing a connection with a network management system,including: obtaining, by a relay node, a first IP address of the relaynode; obtaining, by the relay node, an IP address of a security gatewayby using the first IP address of the relay node; establishing, by therelay node, an IP security tunnel with the security gateway according tothe IP address of the security gateway; obtaining, by the relay node, asecond IP address of the relay node and an IP address of the networkmanagement system through the IP security tunnel; and establishing, bythe relay node, a connection with the network management system by usingthe second IP address of the relay node and the IP address of thenetwork management system.

An embodiment of the present disclosure further provides a method forestablishing a packet data network connection for a relay node,including: obtaining, by a mobile management entity MME, subscriptiondata of a relay node when the relay node accesses a network, where thesubscription data includes information for instructing selection of apacket data network gateway P-GW for the relay node; and selecting, bythe MME, a P-GW for serving the relay node according to the subscriptiondata, so that the P-GW may establish a packet data network (PDN)connection for the relay node.

An embodiment of the present disclosure further provides a relay node,including: a first address obtaining unit, configured to obtain a firstIP address of the relay node; a querying unit, configured to obtain anIP address of a security gateway by using the first IP address; asecurity tunnel establishing unit, configured to establish an IPsecurity tunnel with the security gateway according to the IP address ofthe security gateway; a second address obtaining unit, configured toobtain a second IP address of the relay node and an IP address of anetwork management system through the IP security tunnel; and aconnection establishing unit, configured to establish a connection withthe network management system by using the second IP address of therelay node and the IP address of the network management system.

An embodiment of the present disclosure further provides a mobilemanagement network element, including: a subscription data obtainingunit, configured to obtain subscription data of a relay node when therelay node accesses a network, where the subscription data includesinformation for instructing selection of a packet data network gatewayP-GW for the relay node; and a gateway selection unit, configured toselect a P-GW for serving the relay node according to the subscriptiondata, so that the P-GW establishes a packet data network PDN connectionfor the relay node.

An embodiment of the present disclosure further provides a communicationsystem, including: a network management system and a relay node, wherethe relay node is configured to establish a connection with the networkmanagement system.

In the method, the device, and the communication system for establishinga connection with a network management system provided by theembodiments of the present disclosure, the relay node obtains the firstIP address of the relay node by using the PDN connection; obtains the IPaddress of the security gateway by using the first IP address of therelay node; establishes the IP security tunnel with the security gatewayaccording to the IP address of the security gateway; obtains the secondIP address of the relay node and the IP address of the networkmanagement system through the IP security tunnel; and establishes theconnection with the network management system by using the second IPaddress of the relay node and the IP address of the network managementsystem. Consequently, during the process of accessing a network, therelay node implements a connection with the network management system,and the security of the connection and the processing of establishingthe connection is ensured. This further ensures that the relay node iscapable of downloading necessary configuration parameters from thenetwork management system to perform access and configuration of therelay node.

BRIEF DESCRIPTION OF DRAWINGS

To illustrate the technical solutions in the embodiments of the presentdisclosure or in the prior art more clearly, the following brieflyintroduces the accompanying drawings required for describing theembodiments. The accompanying drawings in the following description showmerely some embodiments of the present disclosure, and persons ofordinary skill in the art may still derive other drawings from theseaccompanying drawings without creative efforts.

FIG. 1 is a schematic diagram of a network architecture after a relaynode is introduced in an E-UTRAN network according to an embodiment ofthe present disclosure;

FIG. 2 is a flowchart of a method for establishing a connection with anetwork management system according to an embodiment of the presentdisclosure;

FIG. 3 is a flowchart of message exchange during establishment of aconnection between a relay node and a network management systemaccording to an embodiment of the present disclosure;

FIG. 4 is a flowchart of a method for establishing a packet data networkconnection for a relay node according to an embodiment of the presentdisclosure;

FIG. 5 is a schematic structural diagram of a relay node according to anembodiment of the present disclosure;

FIG. 6 is a schematic structural diagram of a mobile management networkelement according to an embodiment of the present disclosure; and

FIG. 7 is another schematic structural diagram of the mobile managementnetwork element according to an embodiment of the present disclosure.

DESCRIPTION OF EMBODIMENTS

In order to make persons skilled in the art understand the solutions ofthe embodiments of the present disclosure more clearly, the embodimentsof the present disclosure are further described in detail in thefollowing with reference to the accompanying drawings and implementationmanners.

In an E-UTRAN network, after the introduction of a relay node, thenetwork architecture is shown in FIG. 1.

In the network architecture, a relay node (such as RN1, RN2, RN3, andRN4 in FIG. 1) accesses the network through a Donor base station (DonoreNB, DeNB), and the relay node is similar to a user equipment (UserEquipment, UE). The relay node also establishes a connection with amobile management entity (Mobile Management Entity, MME) and a servicegateway (S-GW) during the network access process of the relay node.Meanwhile, as a network element device, the relay node furtherestablishes a connection with a network management system and downloadconfiguration parameters, so as to enable relevant functions of therelay node so that the user equipment (such as UE1, UE2, UE3, UE4, andUE5 in FIG. 1) may access the network.

To establish connectivity with the network management system, the relaynode establishes a PDN (packet data network) connection first toestablish basic IP (Internet Protocol) connectivity between the relaynode and a core network. The PDN connection is associated with aspecific packet data network gateway (PDN Gateway, P-GW). That is, theuser equipment performs data exchange with the packet data network PDNthrough the P-GW. Different from the process of establishing a PDNconnection for a common user equipment, establishing the PDN connectionby the relay node is used to provide a connection between the relay nodeand the network management system and a connection between the relaynode and a network where the network management system is located. Thenetwork management system and the network where the network managementsystem is located are possessed by an operator and are protected forsecurity. To ensure the IP accessibility between the relay node and thenetwork management system, a P-GW is specified. That is, when performingselection of a P-GW during the process of establishing a PDN connection,the MME selects a P-GW that is capable of supporting the IPaccessibility between the relay node and the network where the networkmanagement system is located. Meanwhile, when establishing a session,the P-GW also performs a corresponding processing operation according toa network management service type specified by the MME.

In a network access process of a relay node, the following two phasesare included.

Phase 1: In this phase, the relay node is used as a UE to access anetwork, and the relay node may access any base station which may be acommon evolved base station (Evolved Node B, eNB) or a Donor basestation (Donor eNB, DeNB). In this phase, the relay node establishes aconnection with a network management system, and then downloads a DeNBcell list and other configuration parameters from the network managementsystem.

Phase 2: After obtaining the DeNB cell list, the relay node selects aDeNB cell from the DeNB cell list and accesses the cell. In this phase,the relay node accesses a DeNB and the DeNB selects for the relay nodean MME that is capable of supporting relay. In this phase, the relaynode also keeps or establishes connectivity with the network managementsystem.

In phase 1, when the relay node accesses the network, the MME considersthe relay node as a UE. In the network access process of a UE defined bypresent standards, the UE establishes a PDN connection to a P-GW, andobtains, through the PDN connection, the IP connectivity forcommunicating with a specified PDN. Therefore, the MME needs to select aP-GW for serving the UE. In the prior art, the principle of selecting aP-GW for a UE is as follows: each piece of PDN subscription dataincludes an access point name (Access Point Name, APN) and a gateway(Gateway, GW) identifier; in general, the MME uses the gatewayidentifier information to select the P-GW for serving the UE; however,if the gateway identifier information is not included, the MMEconstructs a corresponding APN-fully qualified domain name (APN-FullyQualified Domain Name, N-FQDN) according to the APN in the PDNsubscription data, and then obtains an address of the P-GW from a domainname server (Domain Name Server, DNS) according to the APN-FQDN.

For the relay node, because the relay node establishes IP connectivitywith the network where the network management system is located and theP-GW for serving the relay node supports IP accessibility between therelay node and the network where the network management system islocated, an existing method for selecting a P-GW for a UE cannot be usedto select a P-GW for serving a relay node that accesses a network.

In addition, the relay node further obtains address information of thenetwork management system, and the network management system may beoperator-level or equipment-vendor-level. The relay node is capable ofestablishing a connection with the network management system only afterobtaining the information. In addition, to avoid that the informationabout the network management system is illegally obtained or modified bya third party in the process of establishing a connection between therelay node and the network management system, a relevant mechanism isneeded to ensure the secure transmission of the information.

To solve the foregoing problem, in the method, the device, and thenetwork for establishing a connection with a network management systemin the embodiments of the present disclosure, a relay node obtains afirst IP address of the relay node by using a PDN connection; the relaynode obtains an IP address of a security gateway by using the first IPaddress of the relay node; the relay node establishes an IP securitytunnel with the security gateway according to the IP address of thesecurity gateway; the relay node obtains a second IP address of therelay node and an IP address of the network management system throughthe IP security tunnel; and the relay node establishes a connection withthe network management system by using the second IP address of therelay node and the IP address of the network management system. Becauseit is on a protected IP security tunnel that the relay node obtainsaddress information of the network management system, not only is theconnection between the relay node and the network management systemimplemented, but also secure and correct transmission of the informationabout the network management system is ensured.

FIG. 2 is a flowchart of a method for establishing a connection betweena relay node and a network management system according to an embodimentof the present disclosure.

Step 201: A relay node obtains a first IP address of the relay node.

Optionally, the obtaining, by a relay node, a first IP address of therelay node includes: obtaining, by the relay node, the first IP addressby using a Dynamic Hosting Configuration Protocol (Dynamic HostingConfiguration Protocol, DHCP) process. For example, after establishing aPDN connection, the relay node obtains its own IP address through a DHCPprocess, namely, the first IP address of the relay node. For thespecific DHCP process, reference may be made to the prior art, which isnot described herein again. Alternatively, the relay node obtains thefirst IP address of the relay node through a process of establishing aPDN connection. For example, in the process of establishing the PDNconnection, a P-GW directly assigns an IP address to the relay node,namely, the first IP address of the relay node.

Step 202: The relay node obtains an IP address of a security gateway byusing the first IP address of the relay node.

Optionally, the relay node may make a query to the DNS by using an FQDN(Fully Qualified Domain Name) that includes information about thenetwork management system and obtain the IP address of the securitygateway. For example, in a specific implementation process, by sendingan FQDN that includes information about the network management system tothe DNS to make a query, the relay node obtains the IP address of thesecurity gateway fed back by the DNS.

The network management system may be any one or more of the followingidentification information: a device identifier of the relay node, adevice manufacturer identifier of the relay node, an operatoridentifier, and a network management system identifier, where the deviceidentifier of the relay node may be the hardware address, the hardwarenumber, the device card number, or the device number of the relay node.

For example, the FQDN constructed by the relay node may include one ormore of the foregoing identifiers. The multiple identifiers areconnected by a “.”. Certain non-limitative examples (“< >” andcharacters in < > are an annotation) are provided in the following:

relay<indicating a relay node>0.123456<indicating the device identifierof the relay node>.XX . . . . ;

relay<indicating a relay node>.AAA<indicating the device manufactureridentifier of the relay node>.XX . . . . ;

oam<indicating a network management system>.AAA<indicating the devicemanufacturer identifier of the relay node>.XX . . . . ;

oam<indicating a network management system>.BBB<operator identifier>.XX. . . . ; and

oam<indicating a network management system>0.123456<indicating thedevice identifier of the relay node>.XX . . . .

In some implementations, the relay node may further use a DHCP processthat includes the information about the network management system tomake a query to the DHCP server and obtain the IP address of thesecurity gateway. For example, in one implementation process, by sendinga DHCP message that includes the information about the networkmanagement system to the DHCP server for making a query, the relay nodeobtains the IP address of a security gateway fed back by the DHCPserver.

The network management system may be any one or more of the followingidentification information: a device identifier of the relay node, adevice manufacturer identifier of the relay node, an operatoridentifier, and a network management system identifier. The deviceidentifier of the relay node may be the hardware address, the hardwarenumber, the device card number, or the device number of the relay node.In a specific implementation process, the information may be included ina DHCP option (DHCP option) field in a DHCP request message forrequesting or querying for specific information from the DHCP server.

In the embodiment of the present disclosure, the network managementsystem may be an operator-level network management system, andcorrespondingly, the IP address of a security gateway fed back by theDNS or the DHCP server is an IP address of a security gateway that isassociated with the network where the operator-level network managementsystem is located; or, the network management system may further be adevice-manufacturer-level network management system, andcorrespondingly, the IP address of a security gateway fed back by theDNS or the DHCP server is an IP address of a security gateway that isassociated with the network where the device-manufacturer-level networkmanagement system is located.

In some embodiments, the association described herein means that thenetwork where the network management system is located can be accessedonly through the security gateway. The network where the networkmanagement system is located includes: an actual IP (subnet) networkwhere the network management system is located, or an IP (subnet)network that performs interconnection communication with the actual IP(subnet) network where the network management system is located. Thenetwork in the embodiment of the present disclosure is protected by asecurity gateway.

Step 203: The relay node establishes an IP security tunnel with thesecurity gateway according to the IP address of the security gateway.

The IP address of the security gateway is used for addressing thesecurity gateway. In the process of establishing the IP tunnel betweenthe relay node and the security gateway, the relay node performsauthentication with the security gateway and establishes, after theauthentication is successful, the IP security tunnel with the securitygateway. Certain existing implementation manners may be used for theauthentication and the process of establishing the IP security tunnel,which is not limited by the embodiment of the present disclosure.

Step 204: The relay node obtains a second IP address of the relay nodeand an IP address of the network management system through the IPsecurity tunnel.

In this step, the second IP address of the relay node is an IP addressused for network management service transmission for the relay node andmay be obtained by initiating a DHCP process to the network where thenetwork management system is located on the IP security tunnel.

The IP address of the network management system may be obtained by usingany one of the following three manners:

(1) The relay node initiates a DHCP process to the network where thenetwork management system is located on the IP security tunnel to obtainthe IP address of the network management system. That is, the relay noderequests the IP address of the network management system from the DHCPserver through a DHCP process. To be specific, information about thenetwork management system may be included in a DHCP option (DHCP option)field in a DHCP request message, and the DHCP server directly feeds backthe IP address of the network management system.

(2) The DHCP server feeds back an FQDN that indicates the networkmanagement system to the relay node, and then the relay node uses theFQDN to make a query to the DNS on the IP security tunnel so as toobtain the IP address of the network management system fed back by theDNS.

(3) The relay node uses an FQDN that includes information about thenetwork management system to make a query to the DNS on the IP securitytunnel so as to obtain the IP address of the network management system.

The information about the network management system may be any one ormore of the following information: a device identifier of the relaynode, a device manufacturer identifier of the relay node, an operatoridentifier, and a network management system identifier. The deviceidentifier of the relay node may be the hardware address, the hardwarenumber, the device card number, or the device number of the relay node.

The process of constructing an FQDN and the process of making a query tothe DNS are similar to the operations in step 202, which are notdescribed herein again.

Step 205: The relay node establishes a connection with the networkmanagement system by using the second IP address of the relay node andthe IP address of the network management system.

In this step, the established connection is implemented through the IPsecurity tunnel between the relay node and the security gateway, and theestablishment of the connection may be initiated by the relay node or bythe network management system.

FIG. 3 is a flowchart of message exchange during establishment of aconnection between a relay node and a network management systemaccording to an embodiment of the present disclosure.

Step 301: A relay node obtains a first IP address of the relay nodethrough a process of establishing a PDN connection.

Step 302: The relay node initiates a request to a DNS by using an FQDNthat includes information about a network management system, orinitiates a request to a DHCP server by using a DHCP request messagethat includes information about a network management system.

Step 303: The relay node receives an IP address of a security gatewayfed back by the DNS or the DHCP server to the relay node.

Step 304: The relay node establishes an IP security (SecurityArchitecture for IP network, IPSec) tunnel between the relay node andthe security gateway by using the first IP address of the relay node andthe IP address of security gateway.

In this step, the IP address of the security gateway is used foraddressing the security gateway. An existing mechanism may be used inthe authentication between the relay node and the security gateway andin the process of establishing the IPSec channel.

Step 305: The relay node obtains a second IP address of the relay nodeand an IP address of the network management system by initiating a DHCPprocess through the IPSec tunnel.

In this step, the relay node obtains the second IP address of the relaynode used for network management service transmission through the DHCPprocess.

The IP address of the network management system may be obtained by usingany one of the following three techniques:

(1) Initiate a DHCP process to the network where the network managementsystem is located on the IP security tunnel so as to obtain the IPaddress of the network management system, that is, request the IPaddress of the network management system from the DHCP server through aDHCP process. To be specific, have information that indicates thenetwork management system included in a DHCP option (DHCP option) fieldin a DHCP request message, and the DHCP server directly feeds back theIP address of the network management system.

(2) The DHCP server feeds back a fully qualified domain name FQDN thatindicates the network management system, and the fully qualified domainname FQDN that indicates the network management system is used to make aquery to the domain name server DNS on the IP security tunnel and obtainthe IP address of the network management system fed back by the DNS.

(3) Use an FQDN that includes information about the network managementsystem to make a query to the DNS on the IP security tunnel to obtainthe IP address of the network management system.

Step 306: The relay node establishes a connection with the networkmanagement system by using the second IP address of the relay node andthe IP address of the network management system.

As shown in FIG. 3, the IP connection established between the relay nodeand the network management system is implemented through the IP securitytunnel between the relay node and the security gateway; and theestablishment of the IP connection may be initiated by the relay node orby the network management system.

In the method for establishing a connection with a network managementsystem provided by the embodiment of the present disclosure, the relaynode obtains the first IP address of the relay node, obtains the IPaddress of the security gateway by using the first IP address of therelay node, establishes the IP security tunnel with the securitygateway, obtains the second IP address of the relay node and the IPaddress of the network management system used for network managementservice transmission through the IP security tunnel, and establishes aconnection with the network management system by using the second IPaddress of the relay node and the IP address of the network managementsystem. Consequently, during the process of accessing a network, therelay node implements a connection with the network management system,and the security of the connection and the processing of establishingthe connection is ensured. This further ensures that the relay node iscapable of downloading necessary configuration parameters from thenetwork management system to perform access and configuration of therelay node.

In the embodiment of the present disclosure, a PDN connection used fornetwork management service transmission is required for establishing theconnection between the relay node and the network management system,where the PDN connection is established by a P-GW for serving the relaynode and the selection of a P-GW is performed by an MME. A plurality ofimplementation manners may be used for selecting a P-GW for serving therelay node, which is not limited in the embodiment of the presentdisclosure. Several examples are provided in the following for adetailed description.

For example, information for instructing the selection of the P-GW forthe relay node may be set in the subscription data of the relay node. Inthis way, when the relay node accesses a network, the MME may select theP-GW according to the subscription data of the relay node, and initiatesession establishment request to the selected P-GW. The sessionestablishment request includes an APN. The APN is from the subscriptiondata of the relay node and may include a network management servicelabel so that the P-GW establishes a PDN connection according to thenetwork management service label.

FIG. 4 is a flowchart of a method for establishing a packet data networkconnection for a relay node according to an embodiment of the presentdisclosure.

Step 401: When a relay node accesses a network, an MME obtainssubscription data of the relay node. The subscription data includesinformation for instructing selection of a P-GW for the relay node.

The subscription data refers to PDN subscription data, the informationfor instructing the selection of the P-GW for the relay node. Accordingto different access scenarios of the relay node, the information mayhave a plurality of manners. For example, the information may be one orany combination of the following:

(1) an IP address which corresponds to a specific P-GW and is set in aP-GW identifier, where the specific P-GW supports establishing an IPconnection to a network management system;

(2) a set fully qualified domain name, including a hostname of the P-GWthat includes a P-GW information identifier and a public land mobilenetwork (Public Land Mobile Network, PLMN) where the P-GW is located,where the P-GW information identifier includes one or more of thefollowing information: a group identifier, a gateway identifier, agateway type, and gateway information;

(3) a new label added in the APN network identifier (The APN NetworkIdentifier, APN-NI) that is included in the subscription data, or a newservice label added in the APN-NI; and

(4) a specific identifier added in the APN operator identifierreplacement (The APN Operator Identifier replacement, APN-OIreplacement) that is included in the subscription data, where the APN-OIreplacement may be a UE-level APN-OI replacement or an APN-level APN-OIreplacement.

A process for the MME, in different scenarios, to select a P-GW for therelay node according to the information is described in detail below.

Step 402: The MME selects a P-GW for serving the relay node according tothe subscription data, so that the P-GW establishes a packet datanetwork PDN connection for the relay node.

After selecting the P-GW for serving the relay node, the MME initiates asession establishment request to the selected P-GW. The sessionestablishment request includes an APN, and the APN is from thesubscription data of the relay node and may include a network managementservice label so that the P-GW establishes a PDN connection according tothe network management service label.

After the selection of the P-GW is performed, the selection of an S-GWmay be performed by following an existing criterion. Then, the MME mayinitiate a session establishment request to the P-GW through the S-PW.The request includes a corresponding APN, and the APN is used forindicating a type of a service transmitted through the PDN connectionestablished by the P-GW.

In the prior art, the P-GW, according to a service label in the APN-NI,identifies the type of the service transmitted through the PDNconnection that needs to be established.

In the embodiment of the present disclosure, for the purpose that theP-GW may identify the type of the service transmitted through the PDNconnection to be established, a new service label may be defined for therelay node in the APN for indicating that a PDN connection that may beused for network management service transmission is to be established.

It has been mentioned above that, in the embodiment of the presentdisclosure, the information which is used for instructing the selectionof the P-GW for the relay node and is included in the subscription datamay have a plurality of implementation manners. The process for the MME,in different scenarios, to select the P-GW for the relay node accordingto the information is described in detail in the following.

Scenario 1: Supposing that the relay node establishes the PDN connectionin phase 1 of the network access of the relay node, an existing processof selecting a P-GW when a UE access a network is used in the process ofselecting the P-GW. That is, the MME selects a P-GW for the relay nodeaccording to information in the PDN subscription data in a homesubscriber server (Home Subscriber Server, HSS). In the prior art, foreach subscribed PDN, information provided by the HSS includes:

(1) a P-GW identifier and an access point name (Access Point Name, APN);or

(2) an APN and an indication for the APN, where the indication indicateswhether it is allowed that a visited PLMN (Visited PLMN, VPLMN) assignsa P-GW or only a home PLMN (Home PLMN, HPLMN) may assign a P-GW; and

(3) the HSS further indicates the corresponding subscribed PDN of whichAPN is the default APN of the UE.

However, because the relay node needs to establish a connection to thenetwork management system, the P-GW selected for the relay node shouldbe capable of supporting IP connectivity for connecting the networkmanagement system and be capable of establishing a PDN connection to thenetwork management system for the relay node. Therefore, the P-GW shouldbe a specific P-GW and should be differentiated from other common P-GWsduring the selection of the P-GW, and the location of the P-GW is notlimited and may be in a core network.

Base on this situation, in the embodiment of the present disclosure,information in the existing PDN subscription data may be modified toinclude information for instructing selection of a P-GW for the relaynode. As a result, when the relay node accesses a network, the MME maydirectly select a P-GW according to the information in the PDNsubscription data. Specifically, information in the P-GW identifier maybe modified, and information in the APN may also be modified. The twoimplementation manners are described in detail in the following:

1. Modify information in the P-GW identifier to have the information forinstructing the selection of the P-GW for the relay node included in theP-GW identifier. As a result, when the relay node accesses a network,the MME may directly select a P-GW by using the information in the P-GWidentifier, which may specifically include the following implementationmanners:

(1) Set a specific IP address in the P-GW identifier in the PDNsubscription data. The IP address corresponds to a specific P-GW in thecore network. The MME may locate the specific P-GW by using the IPaddress. That is, when the relay node accesses a network, the MME usesthe IP address in the P-GW identifier in the subscription data of therelay node as the address of the P-GW for serving the relay node.

(2) Define a special FQDN in the PDN subscription data. When the relaynode access a network, the MME requests, according to the FQDN, an IPaddress corresponding to the FQDN from the DNS. The IP address is theaddress of the P-GW for serving the relay node.

The FQDN refers to a hostname plus a full path. The fully qualifieddomain name may logically accurately indicate where a host is, that is,the fully qualified domain name is a complete presentation form of ahostname. Information included in the fully qualified domain name mayspecify the location of the host in a domain-name tree.

In the prior art, an FQDN consists of Destination-Host(Destination-Host) and Destination-Realm (Destination-Realm), where:

Destination-Host includes a hostname (hostname) of a target P-GW,meeting the following format:<“topon”|“topoff”>.<single-label-interface-name>.<canonical-node-name>,in which, <“topon”|“topoff”> indicates whether to preferably select aP-GW that has a closer topological distance or shares the same addresswith a service gateway (Service GW, S-GW); <single-label-interface-name>indicates a port type, such as Eth-0 or S8; and <canonical-node-name>indicates description of the P-GW node; and

Destination-Realm consists of the following formats:

epc.mnc<MNC>.mcc<MCC>.3gppnetwork.org, in which, mite and mcc indicatewhich PLMN the P-GW is located in.

For the purpose of differentiating from a P-GW for serving a UE, in theembodiment of the present disclosure, the information for instructingthe selection of the P-GW for the relay node may be added in the FQDN ofan existing P-GW, so that the MME requests, through the FQDN, a theaddress of the P-GW to the DNS for serving the relay node. Specifically,the Destination-Host may include a P-GW information identifier. Forexample, the following one or more identifiers may be included: a groupidentifier, a gateway identifier, a gateway type, location information,and so on.

For example, in the embodiment of the present disclosure, the FQDN ofthe P-GW for serving the relay node may be:topon.S5.cluster4relay.net27.example.net; “cluster4relay” in this fullyqualified domain name identifies a P-GW group that supports relay nodetransmission;

may be: topon.Eth-0.gw32.california.west.example.com, in which, “gw32”is a gateway identifier and is used for indicating a specified P-GW (theP-GW is capable of supporting relay node transmission);

may be topon.vip.relay.california.west.example.com, in which, “relay”identifies a special gateway type that is used for supporting a relaynode transmission; or

may be: topon.S8.gw35.shanghai.pudong.XXroad.example.com, in which,“shanghai.pudong.XXroad” identifies a P-GW that is located at aspecified position (the P-GW is capable of supporting relay nodetransmission).

2. Modify information in the APN to include information for instructingselection of a P-GW for the relay node. As a result, when the relay nodeaccesses a network, the MME may construct an APN-FQDN according to theAPN provided by the HSS and then find, through the DNS by using theAPN-FQDN, the P-GW for serving the relay node.

It should be noted that a plurality of P-GWs, such as P-GWs of a certaintype, may be obtained according to the APN-FQDN. In this situation, theMME may select a proper P-GW among the P-GWs. The specific way to selectthe P-GW is not limited by the embodiment of the present disclosure andmay be determined according to specific application requirements.

In the prior art, an APN consists of the following parts: APN-NI andAPN-OI.

The APN-NI defines an external PDN network connected to the P-GW, whichmay be implemented through the following manners:

the APN corresponds to an FQDN used for selecting a specified gatewaygeneral packet radio service (General Packet Radio Service, GPRS)support node (Gateway GPRS Support Node, GPRS support node, GGSN)/P-GW,and the GGSN/P-GW is capable of understanding that the APN is used foraccessing a specified service (during establishment of a bearer); or

the APN-NI consists of three or more labels and starts with a specifiedservice label; or the APN-NI consists of an independent service label,used for indicating a feature of a service requested by the GGSN/P-GW.

The APN-OI defines where the P-GW is located in an evolved packet system(Evolved Packet System, EPS) network. The APN-OI consists of threelabels, meeting the following formats: “mnc<MNC>.mcc<MCC>.gprs”, inwhich, the first label MNC and the second label MCC together uniquelyidentify a GPRS/EPS PLMN, and the last label must be “gprs”. Eachoperator has a default APN-OI. The default APN-OI may be obtained froman international mobile subscriber identity (International MobileSubscriber Identity, IMSI).

In addition, the subscription data further includes an APN-OIreplacement field, which has the same construction with the defaultAPN-OI. The role that the APN-OI replacement plays is to replace thedefault APN-OI part during DNS addressing. The APN-OI replacementfurther includes other additional labels, which are separated with “.”.

In the embodiment of the present disclosure, for the purpose ofdifferentiating from selecting a P-GW for a UE, related parameters inthe subscription data may be modified, specially including the followingimplementation manners:

(1) Modify the APN-NI.

In some embodiments, a new label may be defined in the APN-NI, and thelabel is used for indicating that the P-GW is selected for the relaynode. For example, the label may be a relay node identifier (RN, relay),a device identifier (IMSI, IMEI, device number, and so on), a gatewayidentifier (relayGW), and so on; or a new service label may be definedin the APN-NI, and the service label is used for indicating selection ofa P-GW for the relay node, for example, the service label may be OAM.

In some embodiments, the defined new service label may be used only by aspecific P-GW, or may also be defined as a service label uniformly usedin the entire network, which is not limited by the embodiment of thepresent disclosure.

(2) Modify the APN-OI Replacement.

The APN-OI replacement is used to replace the default APN-OI part duringDNS addressing. In the embodiment of the present disclosure, a specialAPN-FQDN may also be constructed by modifying the APN-OI replacement,and address information of the P-GW for serving the relay node may beobtained through the APN-FQDN. Specifically, a specified identifier maybe added in the APN-OI replacement. The specified identifier is used forindicating selection of a P-GW for the relay node, and the specifiedidentifier may be a relay node identifier (RN, relay), a deviceidentifier (IMSI, IMEI, device number, and so on), a gateway identifier(relayGW), and so on.

In some embodiments, the subscription data of the HSS includes twoAPN-OI replacement fields, one UE-level APN-OI replacement (on an outerlayer) and one APN-level APN-OI replacement (in each piece of PDNsubscription data). The two APN-OI replacement fields play the samerole. The UE-level APN-OI replacement is applied to all APNs, but theAPN-level APN-OI replacement has a higher priority, that is, when theAPN-level APN-OI replacement appears, this value needs to be used toconstruct the APN-FQDN. The APN-OI replacement mentioned in theembodiment of the present disclosure includes the foregoing twosituations.

Scenario 2: Suppose that the relay node after detachment initiates a newprocess of establishing a PDN connection. In this process, the relaynode initiates a request for establishing a PDN connection to the MME,and the request includes a requested APN. In this scenario, the relaynode may access an MME that does not support a relay node or an MME thatcan support a relay node. These two situations are describedrespectively in the following.

1. The relay node accesses an MME that does not support a relay node.

In this situation, the MME determines whether the APN reported by therelay node is the APN in the subscription data of the relay node, and ifyes, constructs an APN-FQDN according to the APN reported by the relaynode, specifically as follows:

First, the MME uses the APN-OI replacement in the subscription data toreplace the APN-OI part in the APN reported by the relay node, and thenthe MME uses the APN to construct the corresponding APN-FQDN. As aresult, the address information of the corresponding P-GW may beobtained through the DNS according to the APN-FQDN.

In some embodiments, the APN-OI replacement in the subscription data isthe APN-OI replacement added with a specified identifier. As describedabove, the specified identifier is used for indicating selection of aP-GW for the relay node, and the specified identifier may be a relaynode identifier (RN, relay), a device identifier (IMSI, IMEI, devicenumber, and so on), a gateway identifier (relayGW), and so on.

2. The relay node accesses an MME that supports a relay node.

In this situation, the MME also needs to determine whether the APNreported by the relay node is the APN in the subscription data of therelay node. If yes, the following two manners may be used to select aP-GW for the relay node.

(1) Construct an APN-FQDN according to the APN reported by the relaynode, specifically as follows: first, the MME uses the APN-OIreplacement in the subscription data to replace the APN-OI part in theAPN reported by the relay node; meanwhile, if the MME determines thatthe relay node accesses a network in phase 2, an eNB identifier or adevice identifier indication of a Donor base station for serving therelay node need to be added in the APN and may be specifically added inthe APN-NI part or the APN-OI replacement part, and the role is torequest the address of the P-GW located on the Donor base station DeNBfrom the DNS (because it is in phase 2, the MME needs to select a P-GWthat is located on the Donor base station for the relay node); then theMME uses the APN to construct the corresponding APN-FQDN. As a result,the address information of the corresponding P-GW may be obtainedthrough the DNS according to the APN-FQDN.

(2) According to that the request for establishing a PDN connection is arequest for establishing a new PDN connection initiated by the relaynode, the MME may, according to the P-GW selecting result before,directly select a corresponding P-GW for the relay node. The P-GW may belocated in a core network or on a DeNB.

In the embodiment of the present disclosure, when information forinstructing selection of a P-GW for the relay node in the subscriptiondata of the relay node is set so that the relay node accesses a network,the MME may select a P-GW for serving the relay node according to thesubscription data of the relay node, and when initiating a sessionestablishment request to the P-GW, have a network management servicelabel included in an APN of the session establishment request so thatthe P-GW may establish a PDN connection according to the networkmanagement service label.

Correspondingly, an embodiment of the present disclosure furtherprovides a relay node. FIG. 5 is a schematic structural diagram of arelay node according to an embodiment of the present disclosure.

In this embodiment, the relay node includes: a first address obtainingunit 501, a querying unit 502, a security tunnel establishing unit 503,a second address obtaining unit 504, and a connection establishing unit505.

The first address obtaining unit 501 obtains a first IP address of therelay node. The querying unit 502 obtains an IP address of a securitygateway by using the first IP address of the relay node. The securitytunnel establishing unit 503 establishes an IP security tunnel with thesecurity gateway according to the IP address of the security gateway.The second IP address obtaining unit 504 obtains a second IP address ofthe relay node and an IP address of a network management system throughthe IP security tunnel. The connection establishing unit 505 establishesa connection with the network management system according to the secondIP address of the relay node and the IP address of the networkmanagement system.

In some example implementations, the first IP address obtaining unit 501may obtain the IP address of the relay node through a DHCP process, orobtain the IP address of the relay node through a PDN connection.

The second IP address obtaining unit 504 may initiate a DHCP process toa network where the network management system is located on the IPsecurity tunnel to obtain the IP address of a relay node used fornetwork management service transmission; initiate a DHCP process on theIP security tunnel to obtain the IP address of the network managementsystem; or initiate a DHCP process on the IP security tunnel to obtain afully qualified domain name FQDN used for indicating the networkmanagement system, and then use the fully qualified domain name FQDNused for indicating the network management system to make a query to adomain name server DNS on the IP security tunnel and obtain the IPaddress of the network management system fed back by the DNS; or use afully qualified domain name FQDN that includes information about thenetwork management system to make a query to the DNS on the IP securitytunnel and obtain the IP address of the network management system fedback by the DNS.

The network management system may be an operator-level networkmanagement system, and correspondingly, the IP address of the securitygateway is an IP address of a security gateway that is associated withthe network where the operator-level network management system islocated; or the network management system may also be adevice-manufacturer-level network management system, andcorrespondingly, the IP address of the security gateway is an IP addressof a security gateway that is associated with the network where thedevice-manufacturer-level network management system is located.

The association described herein means that the network where thenetwork management system is located can be accessed only through thegateway. The network where the network management system is locatedincludes: an actual IP (subnet) network where the network managementsystem is located, or an IP (subnet) network that performsinterconnection communication with the actual IP (subnet) network wherethe network management system is located. The network where the networkmanagement system is located in the embodiment of the present disclosureis protected by a security gateway.

The network management system may be any one or more of the followingidentifiers: a device identifier of the relay node, a devicemanufacturer identifier of the relay node, an operator identifier, and anetwork management system identifier. The device identifier of the relaynode may be the hardware address, the hardware number, the device cardnumber, or the device number. of the relay node.

The relay node in the embodiment of the present disclosure obtains thefirst IP address of the relay node by using the PDN connection; obtainsthe IP address of the security gateway by using the IP address of therelay node; establishes the IP security tunnel with the security gatewayaccording to the IP address of the security gateway; obtains the secondIP address of the relay node and the IP address of the networkmanagement system through the IP security tunnel; and establishes aconnection with the network management system by using the second IPaddress of the relay node and the IP address of the network managementsystem. Consequently, during the process of accessing a network, therelay node implements a connection with the network management system,and the security of the connection is ensured. This further ensures thatthe relay node is capable of downloading necessary configurationparameters from the network management system to perform access andconfiguration of the relay node.

Correspondingly, an embodiment of the present disclosure furtherprovides a mobile management network element. FIG. 6 is a schematicstructural diagram of the mobile management network element.

In this embodiment, the mobile management network element includes: asubscription data obtaining unit 601 and a gateway selecting unit 602.

The subscription data obtaining unit 601, when a relay node accesses anetwork, obtains subscription data of the relay node, where thesubscription data includes information for instructing selection of aP-GW for the relay node; and the gateway selecting unit 602 select theP-GW for serving the relay node according to the subscription data.

The mobile management network element in the embodiment of the presentdisclosure may further include a session request unit 603. The sessionrequest unit 603 initiates a session establishment request to the P-GWselected by the gateway selecting unit 602. The session establishmentrequest includes an APN in the subscription data of the relay node, andthe APN includes a network management service label so that the P-GWestablishes a PDN connection according to the network management servicelabel.

In the embodiment of the present disclosure, the information forinstructing the selection of the P-GW for the relay node included in thesubscription data may have a plurality of implementation manners, forexample:

(1) The information for instructing the selection of the P-GW for therelay node may be: an IP address corresponding to a specified P-GW setin a P-GW identifier, where the specific P-GW supports establishment ofan IP connection to a network management system.

Correspondingly, in this situation, the gateway selecting unit 602 usesthe IP address in the P-GW identifier in the subscription data as anaddress of the P-GW for serving the relay node.

(2) The information for instructing the selection of the P-GW for therelay node may also be: a set fully qualified domain name, whichincludes: a hostname of a P-GW that includes a P-GW informationidentifier and a PLMN where the P-GW is located, where the P-GWinformation identifier may be any one or more of the followinginformation: a group identifier, a gateway identifier, a gateway type,location information, and so on.

Correspondingly, in this situation, the gateway selecting unit 602 mayobtain an IP address of the fully qualified domain name through a DNS,and use the IP address as the address of the P-GW for serving the relaynode.

(3) The information for instructing the selection of the P-GW for therelay node may also be: a new label added in an APN-NI included in thesubscription data, or a new service label added in the APN-NI.

Correspondingly, in this situation, the gateway selecting unit 602 may,according to the APN-NI and an APN-OI replacement in the subscriptiondata, construct an APN-fully qualified domain name, obtain the IPaddress of the fully qualified domain name of the APN though the DNS,and use the IP address as the address of the P-GW for serving the relaynode.

(4) The information for instructing the selection of the P-GW for therelay node may also be: a specified identifier added in the APN-OIreplacement included in the subscription data.

Correspondingly, in this situation, the gateway selecting unit 602 may,according to the APN-NI in the subscription data and the APN-OIreplacement, construct a fully qualified domain name of the APN, obtainthe IP address of the fully qualified domain name of the APN though theDNS, and use the IP address as the address of the P-GW for serving therelay node.

For the specific implementation of manners of the information forinstructing the selection of the P-GW for the relay node, reference maybe made to the description above, which is not described herein again.

The mobile management network element in the embodiment of the presentdisclosure, when a relay node accesses a network, selects a P-GW forserving the relay node according to information for instructingselection of a P-GW for the relay node in subscription data of the relaynode, and, when initiating a session establishment request to the P-GW,has a network management service label included in an APN in the sessionestablishment request so that the P-GW may establish a PDN connectionaccording to the network management service label.

FIG. 7 is another schematic structural diagram of the mobile managementnetwork element according to an embodiment of the present disclosure.

Compared with the embodiment shown in FIG. 6, in this embodiment, themobile management network element further includes a determining unit701, which, when a relay node initiates establishment of a new PDNconnection, determines whether an APN reported by the relay node is theAPN that the relay node subscribes to.

Correspondingly, in this embodiment, the gateway selecting unit 602 isfurther configured to: after the determining unit 701 determines thatthe APN reported by the relay node is the APN that the relay nodesubscribes to, replace the APN-OI in the APN reported by the relay nodewith the APN-OI replacement in the subscription data of the relay node,construct a fully qualified domain name of the APN according to the APNreported by the relay node wherein the APN-OI of the APN reported isreplaced, obtain the IP address corresponding to the fully qualifieddomain name of the APN through the DNS, and use the IP address as theaddress of the P-GW for serving the relay node.

When the relay node initiates the establishment of the new PDNconnection, the mobile management network element is capable of,according to the request for establishing a new PDN connection initiatedby the relay node, determining that the request is from the relay nodeinstead of a UE. In this situation, the gateway selecting unit 602further adds an eNB identifier or device identifier indication of aDonor base station for serving the relay node in the constructed fullyqualified domain name of the APN so as to request the address of theP-GW located on the Donor base station DeNB from the DNS.

For the situation above, the mobile management network element mayfurther select the P-GW for serving the relay node before. Therefore, inanother embodiment of the mobile management network element, the gatewayselecting unit 602 may further be configured to: after the determiningunit 701 determines that the APN reported by the relay node is the APNthat the relay node subscribes to, select the IP address of the P-GW forserving the relay node before.

The mobile management network element in the embodiment of the presentdisclosure, when a relay node accesses a network, selects a P-GW forserving the relay node according to subscription data of the relay node,and, when initiating a session establishment request to the P-GW, has anetwork management service label included in an APN in the sessionestablishment request so that the P-GW for serving the relay node mayestablish a PDN connection according to the network management servicelabel.

Correspondingly, an embodiment of the present disclosure furtherprovides a communication system, including: a network management systemand the foregoing relay node, where the relay node is configured toestablish a connection with the network management system.

In this communication system, the foregoing mobile management networkelement is further included.

In this communication system, the foregoing P-GW may be further includedfor receiving a session establishment request send by the mobilemanagement network element and establishing a PDN connection accordingto a network management service label included in the sessionestablishment request.

For the specific structures of the relay node and the mobile managementnetwork element, reference may be made to the description above, whichare not described herein again.

The P-GW may be located in a core network or located on a DeNB.

By employing the network for establishing a connection with a networkmanagement system in the embodiment of the present disclosure, in theprocess of accessing a network, the relay node implements a connectionwith the network management system. In addition, security of theconnection is ensured, and it is further ensured that the relay node iscapable of downloading necessary configuration parameters from thenetwork management system to complete the access and configuration ofthe relay node.

The embodiments of the present disclosure are described in detail above.Although the present disclosure is described with reference to exemplaryembodiments, the description of the embodiments is only intended to helpunderstand the method and device of the present disclosure. With respectto the specific implementation manners and application scope,modifications and variations may be made by persons of ordinary skill inthe art according to the idea of the present disclosure. Therefore, thespecification shall not be construed as a limitation to the presentdisclosure.

What is claimed is:
 1. A method for establishing a packet data networkconnection for a relay node, comprising: receiving, by a mobilemanagement entity (MME), when the relay node accesses a network,subscription data of the relay node, wherein the subscription datacomprises information for instructing selection of a packet data networkgateway (P-GW) for the relay node; and selecting, by the MME, a P-GW forserving the relay node according to the subscription data; wherein themethod further comprises: transmitting, by the MME, a sessionestablishment request to the selected P-GW, wherein the sessionestablishment request comprises an access point name (APN), and the APNcomprises a network management service label, wherein the networkmanagement service label is used for the P-GW to establish a packet datanetwork (PDN) connection for the relay node; wherein the information forinstructing the selection of the P-GW for the relay node comprises afully qualified domain name, wherein the fully qualified domain namecomprises a hostname of the P-GW, wherein the hostname includes a P-GWinformation identifier and a public land mobile network (PLMN) where theP-GW is located; and wherein the selecting, by the MME, the P-GW forserving the relay node according to the subscription data comprises:receiving, by the MME, an IP address of the fully qualified domain namethrough a domain name server (DNS) and using the IP address as anaddress of the P-GW for serving the relay node.
 2. The method accordingto claim 1, wherein the P-GW information identifier comprises one ormore of the following information: a group identifier, a gatewayidentifier, a gateway type, and location information.
 3. A method forestablishing a packet data network connection for a relay node,comprising: receiving, by a mobile management entity (MME), when therelay node accesses a network, subscription data of the relay node,wherein the subscription data comprises information for instructingselection of a packet data network gateway (P-GW) for the relay node;and selecting, by the MME, a P-GW for serving the relay node accordingto the subscription data; wherein the method further comprises:transmitting, by the MME, a session establishment request to theselected P-GW, wherein the session establishment request comprises anaccess point name (APN), and the APN comprises a network managementservice label, wherein the network management service label is used forthe P-GW to establish a packet data network (PDN) connection for therelay node; wherein the information for instructing the selection of theP-GW for the relay node comprises a new label added in an access pointname network identifier (APN-NI) that is comprised in the subscriptiondata, or a new service label added in the APN-NI; and wherein theselecting the P-GW for serving the relay node according to thesubscription data comprises: constructing a fully qualified domain nameof the APN according to the APN-NI and an access point name operatoridentifier replacement (APN-OI) replacement in the subscription data;and receiving an IP address of the fully qualified domain name of theAPN through the DNS and using the IP address as an address of the P-GWfor serving the relay node.
 4. A method for establishing a packet datanetwork connection for a relay node, comprising: receiving, by a mobilemanagement entity (MME), when the relay node accesses a network,subscription data of the relay node, wherein the subscription datacomprises information for instructing selection of a packet data networkgateway (P-GW) for the relay node; and selecting, by the MME, a P-GW forserving the relay node according to the subscription data; wherein themethod further comprises: transmitting, by the MME, a sessionestablishment request to the selected P-GW, wherein the sessionestablishment request comprises an access point name (APN), and the APNcomprises a network management service label, wherein the networkmanagement service label is used for the P-GW to establish a packet datanetwork (PDN) connection for the relay node; wherein the information forinstructing the selection of the P-GW for the relay node comprises aspecified identifier added in an access point name operator identifierreplacement (APN-OI) replacement included in the subscription data; andwherein the selecting the P-GW for serving the relay node according tothe subscription data comprises: constructing a fully qualified domainname of the APN according to an access point name network identifier(APN-NI) in the subscription data and the APN-OI replacement; andreceiving an IP address of the fully qualified domain name of the APNthrough a domain name server (DNS) and using the IP address as anaddress of the P-GW for serving the relay node.
 5. The method accordingto claim 4, wherein the APN-OI replacement is a user-equipment-levelAPN-OI replacement or an APN-level APN-OI replacement.
 6. The methodaccording to claim 4, further comprising: determining, by the MME, whenthe relay node initiates establishment of a new PDN connection, the APNreported by the relay node is the APN that the relay node subscribes to;replacing the APN-OI in the APN reported by the relay node with theAPN-OI replacement in the subscription data of the relay node and thenconstructing a fully qualified domain name of the APN according to theAPN reported by the relay node wherein the APN-OI of the APN reported isreplaced; and receiving an IP address of the fully qualified domain nameof the APN through the DNS and using the IP address as the address ofthe P-GW for serving the relay node.
 7. The method according to claim 6,further comprising: adding an Evolved Node B (eNB) identifier or deviceidentifier of a Donor base station for serving the relay node in theconstructed fully qualified domain name of the APN.
 8. A mobilemanagement network element, comprising: a receiver, configured toreceive subscription data of a relay node, wherein the subscription datacomprises information for instructing selection of a packet data networkgateway (P-GW) for the relay node, wherein the information forinstructing the selection of the P-GW for the relay node comprises a newlabel added in the an access point name network identifier (APN-NI) thatis comprised in the subscription data, or a new service label added inthe APN-NI; a processor, configured to construct a fully qualifieddomain name of the APN according to the APN-NI and an access point nameoperator identifier replacement (APN-OI) replacement in the subscriptiondata; the receiver, configured to receive an IP (Internet Protocol)address of the fully qualified domain name of the APN though a domainname server (DNS); and the processor, configured to use the IP addressas an address of the P-GW for serving the relay node.
 9. A mobilemanagement network element, comprising: a receiver, configured toreceive subscription data of a relay node, wherein the subscription datacomprises information for instructing selection of a packet data networkgateway (P-GW) for the relay node, wherein the information forinstructing the selection of the P-GW for the relay node comprises aspecified identifier added in an access point name operator identifierreplacement (APN-OI) replacement comprised in the subscription data; aprocessor, configured to construct a fully qualified domain name of theAPN according to an access point name network identifier (APN-NI) in thesubscription data and the APN-OI replacement; the receiver, configuredto receive obtain an IP (Internet Protocol) address of the fullyqualified domain name of the APN though the DNS; and the processor,configured to use the IP address as an address of the P-GW for servingthe relay node.
 10. The mobile management network element according toclaim 9, further comprising: the processor, configured to determine,when the relay node initiates establishment of a new PDN connection, anAPN reported by the relay node is the APN that the relay node subscribesto; and the processor is further configured to after the processordetermines that the APN reported by the relay node is the APN that therelay node subscribes to, replace the APN-OI in the APN reported by therelay node with the APN-OI replacement in the subscription data of therelay node, and construct a fully qualified domain name of the APNaccording to the APN reported by the relay node wherein the APN-OI ofthe APN reported is replaced; the receiver, configured to receive an IPaddress of the fully qualified domain name of the APN through the DNS;and the processor, configured to use the IP address as the address ofthe P-GW for serving the relay node.
 11. The mobile management networkelement according to claim 10, wherein: the processor is furtherconfigured to add an Evolved Node B (eNB) identifier or deviceidentifier of a Donor base station for serving the relay node in theconstructed fully qualified domain name of the APN.